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(No Model.)

A. 0. ROBBINS CENTRAL STATION COMBINED TELEGRAPH AND TELEPHONE SYSTEM. 11 ,595,241 Patented Dec. 7, 1897.

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UNITED STATES PATENT OEEIcE.

ARTHUR C. ROBBINS, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO EDIVARD C. HUGHES, OF SAME PLACE.

CENTRAL-STATION COMBINED TELEGRAPH AND TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 595,2 I1, dated December '7, 1897. Application filed March 26, 1897. Serial No. 629,346. (No model.)

To a whom it may concern;-

Be it known that I, ARTHUR C. ROBBINS, a citizen of the United States, residing in the city and county of San Francisco, State of California, have invented an Improvement in a Central-Station Combined Telegraph and Telephone System; and I hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to improvements in central-station combined telegraph and telephone signal system. It is especially applicable to fire and police telegraphs; an d it consists in the parts and the arrangement and combination of parts hereinafter described and claimed.

Figure 1 is a diagrammatic view showing complete circuit as central and sub station connections with the switch closed. Fig. 2 is a view of the automatic switching device open.

The object of my invention, as stated above, is effected by using two or more relays at the central station with their local contacts arranged to operate on both increase and decrease from the normal current, a transmitting apparatus adapted to increase the mainline battery for signaling the substations, and suitable automatic switches, galvanometers, bells, or other recording apparatus.

B is the main-line battery of the type known as closed circuit or continuous current, and this sends continuously to the line, through the central and sub station apparatus, a current of sufficient strength to attract the armature r of the relay R and to give a normal deflection to the indicator on the index with the galvanometer G. This current, however, is too weak in the normal condition of theline to attract'the armature of the relay R at the central station or that of the relay B at the substation. When in strictly normal condition, the telephone-receiver T of the central station is hung upon the hook of the switch-lever S, and this opens the local telephone-battery contact at C and closes the shunt-contact at C and also the alarm-contact at C The shunt-contact of cuts out the resistance of the central-station apparatus.

In proper normal condition the current from the battery 13 flows through the wire 1, contact C lever K, wire 2, relay It, wire 3, relay R, wire 4, galvanometer Cr, wires 5 and 6, contact C, lever S, wire '7, line-wire to substation, relay R", wires 6 and D, lever S, c011- tact C wire 10, and thence out to the adjoining substation or to earth, as shown in the diagram.

If the substation desires to call the central station, itis only necessary to remove the telephone-receiver T from the hook of the switch S, and this, by the action of a spring or gravity, breaks the contact at C thus increasing the resistance of the main line by the addition of the receiver T and induction-coil I through the wires 11, 12, and 18. This increased resistance so weakens the line as to reduce the magnetic strength of the relay R at the central station, and this releases its armature 0', thus allowing contact to be made at C and causing the bell B to sound an alarm, while the galvanometer deflection at G is reduced so as to show a position of less than normal deflection. Attention being thus attracted at the central station the operator in answering this call removes the receiver T from the hook of the lever S, thus allowing the lever to tilt by spring or gravity. This action opens the contact at C, throwing the central telephone into circuit. It also opens a contact at C which interrupts the bell-circuit and renders the apparatus noiseless while telephoning. It is also noted that the removal of the telephone-receiver T from the hook of the lever S at the substation also closes the contact at C for the local telephonebattery If the central desires to call the substation, it is done by depressing the transmitting-key K. This breaks the circuit at C and cuts the battery 13 out of the circuit, at the same time forming a contact at C which connects the stronger battery B with the line. This increased battery is of sufiicient strength to attract the armature of the relays R and R and cause an alarm or call to be sounded upon the bells B at the central station and B at the substation.

When more than one substation is upon the line, a code of signals is desirable, and they maybe given by certain numbers through the key K, as is customary in fire-alarm signals.

It is customary, as I am aware, to employ the switch S at substations in telephone systems of this class.

In my invention the addition of the switch S at central station with the additional contact C by the use of which silence is secured automatically whenever a telephone is in use and the alarm connections are automatically restored when the receiver is returned to its position on the hook of the lever S, is believed to be novel, and it serves to insure alarm connections at all times either through the bell or through the telephone.

In the apparatus as shown the substation is simply for purposes of illustration and may be replaced by any other desired apparatus. Should the line be open, an alarm will be sounded by the relay R at the central stat-ion. If it grounds or any portion is cut off, the relay R will act to sound an alarm, as above described.

Iaving thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. An improved telegraph and telephone signal system consisting of a central station, a i'nlcrumed lever at said station, a suspended removable receiver and contacts at opposite portions of said lever, alternately made and broken by .the suspension or removal of the receiver, an alarm and a local batterycircuit at the central station for operating the same,

a relay actuated by the main line current and controlling-contacts in said local circuit, and an independent contact with which the said lever engages said last-named contact being closed when the receiver is suspended and open when the receiver is removed, substantially as herein described.

2. In a central-station combined telegraph and telephone signal system, open and closed circuit-batteries of different strength at the central station, a transmitter whereby the weaker battery is normally maintained in continuous connection with the line to the substation, a relay at the substation through which the current passes, a galvanometer the index of which is by said current caused to show a normal deflection, a second relay at the central station and a relay at the substation, the armatures of which are not attracted by the current of the weaker battery, an increased resistance through the receiver of the sub station which is thrown into the line when said receiver is removed from its suspendinghook, whereby the resistance is so increased as to release the armature oi the first-named relay, a contact made by the releasing of said armature whereby the galvanometer deflection is reduced and an alarm sounded at the central station.

3. In a central-station combined telegraph and telephone signal system, batteries of different strengths, the weaker one of which is in normal connection with the main line, a telephone-receiver and a lever by which it is suspended and through which contacts are made when the lever is in its normal position, two of said contacts being broken by the removal of the receiver, whereby the central telephone is thrown into circuit, a transmitting-key with contacts, one of which normally connects the w aker battery with the main line,said contact bei ngbroken and the weaker battery cut out by the depression of: the key, and the other contact which is made at the same time with the breakin of the first-nam ed contact acting to connect the stronger battery with the line, relays at the central and sub stations having bell or alarm connections which are normally non-acting when the weaker battery is in connection with the line, the armatnres of said relays being attracted by the action of the stronger battery when the latter is in line, whereby the alarms are sounded at both central and sub stations.

In witness whereof I have hereunto set my hand.

ARTHUR C. ROBBINS.

lVitnesses:

S. II. Nounsn,

Jnssrn C. Bnonrn. 

